Feed pretreatment for pervaporation process

Abstract

The pervaporative treatment of hydrocarbon feeds which have been exposed to air or oxygen and which contain mixtures of aromatic and non-aromatic hydrocarbons to selectively separate the feed into an aromatics rich stream and a non-aromatics rich stream is improved by the step of pretreating the hydrocarbon feed over an adsorbent such as attapulgite clay.

What is claimed is: 
     
       1. A method for preventing or minimizing flux decline in membrane pervaporation separation of aromatics from feed streams containing mixtures of aromatic(s) and non-aromatic hydrocarbons which feed stream has been exposed to air, said method comprising contacting said feed stream with a polar adsorbent having a cation exchange capacity of at least about 5 meq/100 g of dry adsorbent prior to subjecting the feed to membrane pervaporation separation resulting in the pervaporation process employing said feed to exhibit a constant flux. 
     
     
       2. The method of claim 1 wherein the feed stream is a catalytically processed stream or a catalytically or thermally cracked stream. 
     
     
       3. The method of claim 2 wherein the catalytically processed stream or catalytically or thermally cracked stream boils in the range of about 65° to 1050° F. 
     
     
       4. The method of claim 1, 2 or 3 wherein the feed which was exposed to air or oxygen is deaerated prior to being contacted with the adsorbent. 
     
     
       5. The method of claim 4 wherein the adsorbent is selected from attapulgite clay, alumina and charcoal. 
     
     
       6. The method of claim 1 wherein the adsorbent has a particle size between about 10 to 300 mesh. 
     
     
       7. The method of claim 1, 2 or 3 wherein the contacting of the feed with the adsorbent is for a period of from 1 minute to 5 days.